Causes of Retroplacental Hematoma
The primary causes of retroplacental hematoma include placental abruption, hypertensive disorders of pregnancy (pre-eclampsia/HELLP syndrome), uterine trauma, and coagulation disorders. 1, 2
Definition and Pathophysiology
Retroplacental hematoma (RPH) refers to bleeding that occurs between the placenta and the uterine wall, often as a manifestation of placental abruption. It involves an acute intradecidual vascular accident with rupture of uteroplacental arterioles 3.
Major Causes
1. Hypertensive Disorders
- Pre-eclampsia
- HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets)
- Chronic hypertension
2. Decidual Defects
- Basal plate myometrial fibers (BPMF) - areas where decidua is deficient, allowing direct contact between trophoblast and myometrium 1
- Prior uterine surgery or trauma creating decidual defects
3. Trauma-Related Factors
- Uterine trauma
- External abdominal trauma
- Uterine rupture
4. Coagulation Disorders
- Inherited coagulopathies
- Acquired coagulopathies (e.g., related to amniotic fluid embolism)
5. Obstetric Risk Factors
- Multiple parity (paradoxically appears protective in some studies) 4
- Inadequate prenatal care (fewer than 4 antenatal visits) 4
- Advanced maternal age
- Smoking
- Polyhydramnios
Clinical Presentation and Diagnosis
Retroplacental hematoma may present with:
- Complete clinical syndrome: shock, uterine contracture, absence of fetal heart sounds
- Incomplete syndrome (42.8% of cases): back pain and vaginal bleeding without shock or contracture, with fetal heart sounds still present 5
Diagnostic imaging findings include:
- Ultrasound: linear or biconcave, well-marginated mixed echogenic or anechoic region posterior to the placenta 6
- Secondary signs: intraplacental anechoic regions, intra-amniotic hemorrhage, bulging of the chorionic plate 6
- CT: may show hematoma within the uterine cavity 1
Associated Complications
Retroplacental hematoma is associated with:
- Fetal mortality in utero (13.2 times higher risk) 4
- Low birth weight (<2500g) 4
- Need for blood transfusion 4
- Maternal hemorrhage and potential shock
- Coagulopathy (consumption coagulopathy)
Prevention and Risk Reduction
- Regular, high-quality prenatal care is essential for prevention 4
- Early identification of high-risk patients (those with hypertensive disorders, prior uterine surgery)
- Management of underlying conditions (hypertension, coagulopathies)
Clinical Significance
The frequency of retroplacental hematoma is estimated at 0.13-1.38% of pregnancies 3, with a recent study reporting 5.20% 4. It represents a serious obstetric emergency that can lead to significant maternal and fetal morbidity and mortality if not promptly diagnosed and managed.